Amantadine: what it is and who it helps

Amantadine is a medicine you might hear about for Parkinson’s symptoms and, historically, for influenza A. Today it’s mostly used to help reduce tremor, stiffness, and involuntary movements in Parkinson’s disease and to treat drug-induced movement problems. It used to be an antiviral for flu A, but many flu strains became resistant — so doctors rarely use it for the flu now.

How amantadine works and when it's used

Amantadine works two ways: it affects dopamine signaling in the brain (that’s why it helps some Parkinson’s symptoms) and it has antiviral activity against certain viruses. For Parkinson’s, it can reduce tremor and help with involuntary movements caused by other Parkinson drugs. For movement problems caused by antipsychotics (extrapyramidal symptoms), it can be helpful as well.

If you or a loved one is offered amantadine, expect the prescriber to choose it for mild-to-moderate symptoms or to add it when other treatments cause unwanted movements. For flu, ask your doctor — most public health authorities recommend other antivirals because of resistance.

Dosing, side effects, and safety tips

Typical adult dosing is often 100 mg twice a day (200 mg/day), but doctors adjust this based on kidney function and age. Older adults and people with reduced kidney function usually need lower doses. Don’t double doses if you miss one — check with your clinician about a safe catch-up plan.

Common side effects include dizziness, lightheadedness, dry mouth, constipation, and trouble sleeping. Some people, especially older adults, can get confusion, hallucinations, or swelling in the legs. A distinct skin finding, livedo reticularis (a mottled, purple skin pattern), can appear with long-term use. If you notice sudden muscle stiffness, very high fever, or severe confusion after stopping amantadine, contact a doctor — abrupt withdrawal can cause serious symptoms.

Watch for interactions. Combining amantadine with other drugs that affect the brain (anticholinergics, stimulants, strong dopamine drugs) raises the risk of confusion or movement problems. Tell your prescriber about psychiatric history, heart rhythm issues, or kidney disease before starting. Avoid unverified online pharmacies when buying prescription meds — always use licensed pharmacies and keep regular follow-ups with your provider.

Quick checklist: (1) Ask why it’s recommended for you, (2) confirm dose and kidney adjustments, (3) monitor for dizziness or mood changes, (4) avoid stopping suddenly without medical advice, and (5) only buy from reputable pharmacies. If anything feels off, call your doctor — changes are often manageable if caught early.